This invention relates to a scribe device for forming a scribe line on a surface of a workpiece of brittle material such as a plate glass, ceramics or the like.
In general, in order to break a plate-like workpiece of brittle material, a scribe line is preliminarily formed on a surface of the workpiece so that the workpiece can be broken along this scribe line. A conventional scribe device is disclosed, for example, in Japanese Utility Model Non-examined Publication (Kokai) No. H01-110234. This conventional scribe device includes a disc-like cutter which is sharpened at its peripheral edge, a holder for rotatably supporting the cutter and a pressing/moving mechanism for pressing the cutter against a surface of a plate glass through the holder and moving the cutter along the surface of the plate glass.
In the device having the above-mentioned construction, a scribe line is formed by moving the cutter in a state of the cutter being pressed against the plate glass. However, the conventional device has the following problems. Although, if the force for pressing the cutter against the plate glass is increased, a deep scribe line is formed and the plate glass can be broken easily, a horizontal crack extending leftward and rightward from this scribe line occurs, thus resulting in generation of chips, peel-off and the like in the nearby area of the scribe line. In contrast, if the force for pressing the cutter against the plate glass is decreased, no horizontal crack occurs but a vertical crack is decreased in depth, thus disabling to obtain a favorably breakage of the plate glass.
In view of the above, there is disclosed, in Japanese Patent Non-examined Publication (Kokai) No. H09-25134, a scribe device in which a scribe line is formed on a surface of a workpiece of brittle material by applying a vibration thereto. In this scribe device, an outside barrel of an air cylinder is fixed to a support portion and an inside barrel of the air cylinder is connected to one end of a piezo actuator. The other end of the piezo actuator is connected with a cutter retaining portion. The cutter retaining portion is slidably attached to the support portion through a slider mechanism. The cutter retaining portion is moved up and down in accordance with expansion and contraction of the piezo actuator and a scribe line is formed on a workpiece by vibration caused by the up and down movement of the cutter retaining portion.
In this conventional scribe device, since a side surface of the outside barrel of the air cylinder is fixed to the support portion, a moment is generated. This makes it necessary to employ a slide mechanism in order to transmit a vibration to the workpiece stably.
Examples of a slide mechanism employable in such a scribe device as mentioned above include a slide bearing, a rolling bearing and the like. In general, a rolling bearing is used in view of friction coefficient, etc. The rolling bearing is for supporting a slide motion by causing a rolling body such as a ball and a roller to rotate while supplying a lubricant to the rolling body. Since the vibration of the scribe device reciprocally moves a distance of several microns several hundreds thousand times in one minute, oil shortage occurs. As a consequence, a phenomenon called flaking occurs due to friction between the rolling body and the slider. This shortens the service life of the slider in the scribe device including the slide mechanism. Therefore, the requirement for a longer service life of the scribe device can not be met.
In order to solve the above problems, according to a first aspect of the present invention, there is provided a scribe device comprising a body; a holder; a vibration actuator supported between the body and the holder and generating vibrations in opposing directions thereof; an abutment member retained by one end portion of the holder and for transmitting the vibrations, which have been given to the holder from the vibration actuator, to a workpiece; and a support member for movably supporting the holder on the body of movement in the vibrating directions, wherein the support member includes resilient members which are disposed between the vibration actuator and the abutment member and resiliently deformable only in the vibrating directions.
By virtue of the above constitution, since the holder is supported by the resilient members, there is not need of a provision of a slide mechanism comprising a long rolling bearing or the like between the body and the holder. This enhances a long service life of the device. Moreover, since the resilient members are arranged between the vibration actuator and the abutment member, the lateral swinging of the abutment member could be minimized even if the holder should be laterally swung. Therefore, a stable scribing operation can be obtained.
According to a second aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the first aspect of the present invention, in which the resilient members of the support member bias the holder against the actuator, thereby applying a pre-load to the vibration actuator. Since the resilient members apply the pre-load to the vibration actuator, the abutment member can be vibrated in accordance with the vibration of the vibration actuator and without being affected by reaction from the workpiece. Therefore, a favorable scribing operation can be obtained.
According to a third aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the second aspect of the present invention, in which the body is provided, at an abutment portion where the body is abutted with the vibration actuator, with pre-load adjustment means for adjusting a pre-load to be applied to the vibration actuator. By this, a suitable scribing operation for a particular workpiece can be obtained.
According to a fourth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the third aspect of the present invention, in which the pre-load adjustment means includes an adjustment screw threadingly engaged with the body, the pre-load applied to the vibration actuator being adjusted by adjusting a screwing amount of the adjustment screw. By this, a pre-load adjustment can be made easily by the adjustment screw.
According to a fifth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the first aspect of the present invention, in which each of the resilient members of the support member includes a plate spring. By this, rotation of the holder can be prohibited.
According to a sixth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the fifth aspect of the present invention, in which the plate spring are fixed, at opposite ends thereof, to the body and at a center thereof, to the holder, respectively. By this, the holder can be supported stably.
According to a seventh aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the sixth aspect of the present invention, in which a bent portion is formed between the center and each of the opposite ends of the plate spring where the plate spring is fixed to the body and the holder, respectively. By this, the holder can be supported and can move smoothly in the vibrating directions.
According to an eighth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of one of the first to seventh aspects of the present invention, in which the resilient member includes a ball made of resilient material, the ball being pinchingly held by a pair of spherical receiving seats disposed on the body and the holder. By this, the occurrence of a resonance can be avoided. Therefore, a stable scribing operation can be obtained.
According to a ninth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the first aspect of the present invention, in which the scribe device further comprises a slide support portion, the slide support portion being in opposing relation to the support members in the vibrating directions and arranged, when viewed from the vibration actuator, on the opposite side of the abutment member. By this, the holder can be supported in a more stable manner.
According to a tenth aspect of the present invention, there is provided a scribe device having further features, in addition to the features of the ninth aspect of the present invention, in which the slide support portion comprises a slide holder formed in the holder and having an axis extending along the vibrating directions, and a projection formed on the body in such a manner as to project in the vibrating directions and fitted into the slide hole. By this, the slide support portion can be simplified in structure.